78 results about "Vadose zone" patented technology

A rating evaluation method for groundwater pollution source intensity, including: determining pollution source characteristic indices, and weights and scores thereof, according to the type, the discharge mode, the existence time, and the like of a groundwater pollution source; determining an vadose zone antifouling property index and an vadose zone vulnerability index and scores thereof according to vadose zone characteristics; determining a rating evaluation index system for groundwater pollution sources by combining the pollution source characteristic indices with the vadose zone antifouling property index and the vadose zone vulnerability index; and establishing a rating evaluation method for groundwater pollution source intensity and evaluating the groundwater pollution source intensity. The evaluation method comprehensively considers pollution source characteristics and vadose zone characteristics to accurately reflect source intensities of groundwater pollutants and protect groundwater, and may provide a scientific basis to allow for more scientific and rational protection and management of groundwater.

The present application is directed to a method and apparatus for monitoring soil hydraulic properties, and for collecting soil pore-water samples, in relatively undisturbed soil conditions, by means of a vadose zone probe (10) adapted to be mounted on an inflatable sleeve (18) for installation in a borehole (14) formed in the vadose zone, said vadose zone probe comprises a fluid cell (15) having one or more conduits (13a, 13b, 13c) connected thereto for externally accessing its interior, and a porous medium (11) installed in, or formed on, one of its walls for allowing passage of liquid between the interior of said fluid cell and the borehole soil, wherein said vadose zone probe is made from an elongated body having a front (10f) and rear (10r) sides, and wherein said rear side is substantially flat and said front side is made from a deformable and permeable material, or having a curvature corresponding to the curvature of said borehole.

A method for evaluating underground water pollution source intensity comprises the steps of determining pollution source characteristic indexes according to underground water pollutant types, characteristics and positions and the like; determining vadose zone characteristic indexes according to vadose zone mediums, underground water depth and permeability coefficient and the like; determining an underground water pollution source intensity evaluation index system in combination with pollution source characteristic indexes and vadose zone characteristic indexes; causing the system to analyze underground water pollution source intensity evaluation indexes, establishing a hierarchical structure matrix, and utilizing an analytic hierarchy process to perform weight assignment on the underground water pollution source intensity evaluation indexes; establishing an underground water pollution source intensity grading evaluation method, and evaluating the underground water pollution source intensity. According to the evaluating method, pollution source characteristics and vadose zone characteristics are considered comprehensively, the underground water pollution source intensity is reflected accurately, underground water is protected; the scientific basis can be provided, and the underground water protection and management are more scientific and more rational.

A method and apparatus for collection of pore water samples from a subsurface geologic formation, especially a vadose zone formation having high capillary tension. The method consists of injection of a fluid with known tracer concentrations therein into the formation. The injected displacement fluid develops a wetting front which carries with it the ambient pore water. The mixture of pore water and tracer-bearing displacement fluid is absorbed by a collection system, such as an absorbent member or pumping system. The injection and collection system are attached to a sealing borehole liner for emplacement in a borehole in the formation, and for other functions. Water samples collected in the collector system may be recovered by inversion of the liner, or alternatively by pumping. Samples thus removed from the borehole may be evaluated for chemicals, such as contaminants. The use of the tracer permits pore water characteristics to be distinguished from the motivating displacement fluid. Apparatuses for performing the foregoing functions are described.

Process for assessing and remediation of a contaminated site comprising the steps of assessing the contaminated soil and / or groundwater at a contaminated site involving geophysical scans of the contaminated site and pH, microbial, salinity and metal testing of the soil and / or water contained in the site or other site specific parameters. Remediation of the soil and / or water at the site insitu is followed involving electro-kinetics of the contaminated site. Water testing is carried out during remediation to determine the effect of remediation. Following remediation, an assessment of the remediated soil and water involves electromagnetic scans of the contaminated site as well as pH, microbial, salinity and metal testing of the soil and water contained in the site Once the results of all tests are analysed, the electro-kinetic remediation can be deemed successful or optimized and continued for an extended duration. Effluent water collected from electrodes during remediation can be treated using electrodialysis or suitable technology and then used to flush the vadose zone or reinjected into the groundwater zone the water was extracted from.

The invention discloses a groundwater recharge and infiltration promoting method, and belongs to the technical field of groundwater artificial recharge. According to the method, a recharge tank is artificially dug and built on a high-permeability soil layer, coarse sand serving as an inverted filter backfill material is filled in the recharge tank, exhaust pipes capable of exhausting air in a vadose zone are arranged in the recharge tank and at the periphery of the recharge tank, and the exhaust pipes at the periphery of the recharge tank are exhausted by a vacuum pump. The exhaust pipes and an air extractor are arranged, so that the average infiltration rate of the recharge tank is improved by 4-5 times when groundwater is artificially recharged, and the effect is durable and obvious.

The invention discloses a method of determining fractured horizontal well crack parameters of a low-permeability anisotropic gas reservoir. The method comprises the steps of collecting parameters of reservoir physical properties, fluid properties, a horizontal shaft and proppant properties; dividing the anisotropic gas reservoir into at least two homogeneous vadose zones in the length direction of the horizontal shaft according to transverse permeability distribution, wherein the vadose zones contain artificial cracks; establishing a fractured crack physical model for the vadose zones containing the artificial cracks and a mathematic model for crack parameter evaluation; correcting effective permeability of high-speed non-darcy flow in the cracks; solving a crack yield model considering the high-speed non-darcy flow in the cracks and establishing an evaluation chart for the fractured horizontal well crack parameters of the anisotropic gas reservoir; determining the fractured horizontal well crack parameters of the low-permeability anisotropic gas reservoir. According to the method, comprehensive influences of the anisotropic characteristic of the low-permeability gas reservoir and the high-speed non-darcy flow existing in the fractured horizontal well cracks can be considered, and quick and efficient determination of the parameters of all the cracks of a fractured horizontal well of the low-permeability anisotropic gas reservoir and the proppant size is achieved.

The invention discloses a method and a system for obtaining a relation between groundwater and a natural vegetation system. The method comprises the following steps of: determining a vadose zone strata structure boundary of a researched area, wherein the researched area is a drought or semiarid area; acquiring remote sensing data of the researched area; acquiring vegetation coverage data and groundwater depth and hydrochemical characteristic data of the researched area, which are measured in the field; inverting the remote sensing data of the researched area by utilizing a dimidiate pixel model and acquiring a vegetation coverage image in a satellite pixel scale; generating a groundwater depth and hydrochemical characteristic image in a satellite pixel scale; generating a two-dimensional scatter diagram of a relation between the vegetation coverage and the groundwater depth and the hydrochemical concentration in a satellite pixel scale; and acquiring the relation that the natural vegetation growth is changed with the groundwater depth and the hydrochemical concentration. In the relation between the groundwater and the natural vegetation system, hwich is researched by the invention, spatial scales of research objects are matched; and the relation between the ground water and the natural vegetation system can be effectively and deeply disclosed.

The invention provides a vadose zone soil multi-parameter stratification in-situ monitor, including at least two connection tubes, fixed tubes, at least two monitoring tubes, a tunneling device, and a data transmission and processing system, wherein the data transmission and processing system, the connection tubes, the monitoring tubes and the tunneling device are sequentially connected through the fixed tubes from top to bottom, the connection tubes and the monitoring tubes are alternately distributed; the tunneling device is composed of a drill and a power system; each fixed tube is provided with a fastening thread for fixed connection; each monitoring tube is provided with a multi-parameter sensor and a multi-parameter sensor connector; each connection tube is inside provided with a data transmission line; and the data transmission and processing system receives information transmitted from the multi-parameter sensor connector through the data transmission line, stores, analyzes and displays the information. The in-situ monitor helps to solve the deficiencies in the prior art, and meets the requirements of precise and convenient field monitoring and real-time data output.

Provided is a groundwater pollution source strength evaluation method. The method includes: determining the classified condition of an evaluation site with the combination of the hydrogeological condition around the site according to the construction condition of an industrial site and the implementation condition of seepage prevention measures; dividing the protection grade of vadose zones into three grades of "strong", "medium", and "weak" according to the classified condition of the industrial site, and the thickness and the permeability coefficient of the vadose zones; determining vulnerability indexes and scores of the vadose zones by employing a DRTAS model with the combination of characteristics of the vadose zones, and determining the resistance control classification of the vadose zones according to the protection grade and the vulnerability scores of the vadose zones; determining characteristic indexes of a pollution source and weights thereof by employing overlay and index methods with the combination of characteristics of the pollution source, thereby performing classification of harmfulness of the pollution source; and establishing a groundwater source strength classification evaluation method according to classification matrix coupling, and evaluating the groundwater pollution source strength of the industrial site. According to the method, the groundwater pollution source strength of the industrial site can be accurately evaluated, and scientific basis is provided for the protection and management of groundwater.

An embodiment of the invention provides a groundwater vulnerability assessment method, comprising the steps of selecting an assessment index for determining an assessment index affecting groundwater,wherein the assessment index is at least one of groundwater burial depth, net recharge amount, aquifer medium type, vadose zone medium type, topographic slope, soil salt content and aquifer hydraulicconductivity coefficient; determining the weight of the evaluation index, which is used for determining the influence degree of the evaluation index on the groundwater vulnerability by using the analytic hierarchy process to determine the weight of each evaluation index; the evaluation step being used for calculating the vulnerability index of the research area by superposing the evaluation indexes according to the weights through ArcGIS by using the evaluation indexes and the corresponding weights.

The present application is directed to a method and apparatus for monitoring soil hydraulic properties, and for collecting soil pore-water samples, in relatively undisturbed soil conditions, by means of a vadose zone probe (10) adapted to be mounted on an inflatable sleeve (18) for installation in a borehole (14) formed in the vadose zone, said vadose zone probe comprises a fluid cell (15) having one or more conduits (13a, 13b, 13c) connected thereto for externally accessing its interior, and a porous medium (11) installed in, or formed on, one of its walls for allowing passage of liquid between the interior of said fluid cell and the borehole soil, wherein said vadose zone probe is made from an elongated body having a front (10f) and rear (10r) sides, and wherein said rear side is substantially flat and said front side is made from a deformable and permeable material, or having a curvature corresponding to the curvature of said borehole.

The invention discloses a yield prediction method for a volume fracturing horizontal well of a low-permeability heterogeneous stress-sensitive reservoir stratum. The yield prediction method mainly comprises the following steps that basic parameters of the reservoir stratum, fluid and a horizontal shaft are collected; a heterogeneous gas reservoir is partitioned into at least two vadose zones in the length direction of the horizontal shaft, and the vadose zones include artificial fractures; a vadose unit simulation model of each vadose zone is established; vadose simulation models of at least two vadose units are established; the vadose simulation models of all the vadose units are coupled; time discretization is carried out, the previous five steps are repeated, and the unstable-state yield of the volume fracturing horizontal well of the ultra-low-permeability heterogeneous stress-sensitive reservoir stratum is predicted. According to the technical scheme, the unstable-state yield of the volume fracturing horizontal well of the ultra-low-permeability heterogeneous stress-sensitive reservoir stratum can be predicted, the defects that in the prior art, only homogeneity gas reservoirs can be predicted without consideration of the starting pressure and stress sensitive effects are overcome, and thus the effectiveness and the effect of fracturing transformation of the tight gas reservoir horizontal well are improved.

The invention discloses a collaborative protective mining method for multi-level water resources in a mining area, and relates to the technical field of coal mining. The method comprises the steps that through analyzing layer / division characteristics of a structure of mining overburden strata, the characteristics of a mining-induced stress path in each structural layer and the layer / division characteristics of the permeability of the mining overburden strata, the layer, height, permeability and other parameters of an overburden strata seepage isolation layer are determined; based on an overburden strata ''seepage isolation'' control principle, a mining and separation control effect of the mining parameters and a mining layout method on the multi-level water resources, the collaborative protective mining method for multi-level water resources in the mining area, and a diversion regulating effect are studied, non-destructive monitoring and dynamic evaluation and prediction of water seepage in the surrounding rock at the mining face, the development of cracks in the mining overburden strata, and the change of shallow water level are carried out; and finally a collaborative protectivesystem for multi-level water resources of water blocking of the overburden strata seepage isolation layer, a seepage zone and leakage zone diversion, and collecting water storage of a mined-out area is formed. According to the method, the protection requirements of water amount, ecological water level and water circulation system in an ecologically fragile mining area can be well met, and the application range is wide.

The invention relates to a measurement method of a seepage flow movement rule and belongs to the field of research on basic theory of natural science and vadose zone hydrology. The method comprises the following steps: carrying out field measurement of seepage-in flow and seepage-out flow of stressed section, downstream water level height of the section, upstream water level height of the section, downstream water level distribution area of the section, seepage-out and seepage-in section areas, virtual degree or solidity of the section; then building a relation equation among the quantities according to an opposite and uniform action rule equation set; and finally solving unknown quantities via an equation solving method so as to achieve the purpose of solving practical problems or prediction problems. The measurement method of the seepage flow movement rule has the beneficial effects of showing the theory, the formula and the method for researching, calculating and measuring the seepage flow rule, which conform with the objective laws, enabling the scientific research, experiment and actual measurement of the seepage flow to really embark on a scientific, systematic, theoretical, practical and programmed way, ensuring that the measurement work of the seepage flow rule is not detoured again, and saving manpower, material resources and financial resources.

The invention discloses a water-air two-phase flow simulation experiment device for a two-layer medium. The device comprises a simulation tank, wherein the simulation tank is divided into three cavities including surface water simulation cavities in two sides and a simulation box; the simulation box is filled with a strong-seepage medium and a weak-seepage medium from bottom to top, a plurality of observation tubes and insertion tubes are arranged on the outer wall of the simulation box in one-to-one correspondence, the bottom of each observation tube is communicated with the corresponding insertion tube through a hose, and the insertion tubes are located in different positions of the side surface of the strong-seepage medium. The insertion tubes are inserted into the strong-seepage medium above the ground water level for pressure change observation, and the insertion tubes at the middle-lower part facilitate observation of ground water level change; lifting devices are mounted outside the simulation tank, and fixed-water-head overflow boxes are arranged on the lifting devices to control the surface water level, a tracer filling tube is arranged in the strong-seepage medium, and ascending rules of capillary water are observed. According to the water-air two-phase flow simulation experiment device, the air pressure in a vadose zone is measured according to the stabilized water head differences of U-shaped piezometer tubes, change rules of the air pressure along with time is captured, and the dynamic features of the ground water level after the pressure change are observed according to the water level change of ground water level observation tubes, and the water-air action mechanism is researched.

The invention discloses a test device for vadose zone water flow movement under different buried depths. The test device comprises a measurement cylinder, a balance cup connected to the measurement cylinder and a Mariotte flash connected to the balance cup. The measurement cylinder is internally provided with a weighing sensor, the upper end of the weighing sensor comprises an inverted filter and an undistributed soil column from top to bottom in order, a runoff drain pipe is connected to a position at an equal height to the undistributed soil column on the upper end of the measurement cylinder, a seepage drain pipe is connected to the inside of the balance cup, and the Mariotte flash is internally provided with a third hydraulic sensor for measuring the flow fed from the Mariotte flash to the balance cup. The test device can monitor the surface runoff, soil infiltration capacity and evaporation capacity at the same time, has the characteristics of simple structure and low cost, effectively improves the measurement accuracy, and is convenient to use and repair.

The present invention relates to test technology of a saturated infiltration coefficient of rock and soil of a vadose zone, and a test method for the saturated infiltration coefficient of a drilling constant water head water injection test of the vadose zone is provided on the basis of the effect of the vadose zone infiltration on well hole water infiltration laws. The test method comprises the following steps: the first step, preparing for the test, determining test points and drilling; the second step, determining rock and soil properties and unsaturated infiltration characteristic values; the third step, performing the water injection test, and recording test data; and the fourth step, systemizing the data, and calculating the saturated infiltration coefficient. The method considers the influence of the rock and soil unsaturated infiltration characteristics on well hole infiltration, test results are more accurate; a design calculation table of infiltration coefficients under different pore sizes and soil properties is given, the saturated infiltration coefficient is more convenient to calculate, and the work efficiency is manyfold improved.

The invention discloses a method for determining a railway space line position in a karst mountainous area, and aims to enable a tunnel to integrally pass through a section with lower karst water gushing and mud bursting risks, effectively reduce railway engineering risks in the karst mountainous area, greatly reduce line selection cost and save investigation time limit. The method comprises the following steps: arranging a karst hydrodynamic profile along a karst slope in a direction perpendicular to a river; determining the highest underground water level line; determining a lowest underground water level line; dividing a karst vertical seepage zone, a karst seasonal variation zone and a karst horizontal flowing zone; through coordination and cooperation of spatial line position plane position adjustment and spatial line position longitudinal section position adjustment, enabling a railway tunnel to pass through a middle-low-risk karst vertical seepage zone, avoid a high-risk seasonal variation zone and an extremely-high-risk horizontal flowing zone, or form a herringbone slope surface in a preset tunnel.

This invention is directed to systems including one or more trenches or wells that include one or more perforated pipes through which a gas, such as air, can be injected into the vadose zone of ground located beyond a methaneogenic source to create a positive-pressure gas curtain and / or aerobic conditions in the vadose zone that inhibits migration of and / or facilitate the remediation of mobile volatile organic compounds that are capable of contaminating groundwater surrounding the methaneogenic source.

The invention discloses a method for optimizing the fracture position of an ultra-low permeability heterogeneous gas reservoir fractured horizontal well. The method mainly comprises the following steps that basic parameters of a reservoir stratum, fluid and a horizontal well shaft are collected; a heterogeneous gas reservoir is partitioned into at least to vadose zones in the length direction of the horizontal well shaft, wherein artificial fractures are contained in the vadose zones; a vadose unit simulation model of each vadose zone is established; vadose simulation models of at least two vadose units are established; the vadose simulation models of all the vadose units are coupled, and the yields of the heterogeneous gas reservoir fractured horizontal well are calculated; the yields are compared, and the fracture position where the ultra-low permeability heterogeneous gas reservoir fractured horizontal well has the highest yield is selected. According to the technical scheme, the influences of reservoir stratum heterogeneity and the starting pressure gradient are fully considered, the defect that in the prior art, only the fracture position of a homogeneous gas reservoir fractured horizontal well without the consideration of the starting pressure can be selected is overcome, and thus the effectiveness and the effect of transformation of the ultra-low permeability heterogeneous gas reservoir fractured horizontal well are improved.

A system and method for the accelerated decontamination of contaminated soil, vadose zone and / or groundwater is described. Contaminates are removed from soil and from the groundwater via heat injection through trenching or directionally drilled or horizontally drilled and installed delivery plumbing, pure oxygen injection through separate plumbing installed in the same manner as the plumbing used to deliver the heat, bioventing, sparging, and bioremediation, all through the oxygen delivery plumbing, and soil vapor extraction through vertical wells, all contained in one mobile treatment system. Contaminants are separated from the soil gas via filtration or oxidation. Residual contaminants in the vadose zone and / or the in the groundwater are subjected to volatilization by increased temperature via heat injection and / or oxidation via contaminant degrading microorganisms.

A method and apparatus for collection of pore water samples from a subsurface geologic formation, especially a vadose zone formation having high capillary tension. The method consists of injection of a fluid with known tracer concentrations therein into the formation. The injected displacement fluid develops a wetting front which carries with it the ambient pore water. The mixture of pore water and tracer-bearing displacement fluid is absorbed by a collection system, such as an absorbent member or pumping system. The injection and collection system are attached to a sealing borehole liner for emplacement in a borehole in the formation, and for other functions. Water samples collected in the collector system may be recovered by inversion of the liner, or alternatively by pumping. Samples thus removed from the borehole may be evaluated for chemicals, such as contaminants. The use of the tracer permits pore water characteristics to be distinguished from the motivating displacement fluid. Apparatuses for performing the foregoing functions are described.

The invention discloses a determination method of planar potential replenishment quantity of underground water based on an isotope rainfall effect. The method comprises the steps that a vadose zone interception threshold model is established; a determined rainfall material and an underground water material are brought into the vadose zone interception threshold model for solving; vadose zone interception water quantity, namely minimum replenishment rainfall of the underground water is obtained; and then the potential replenishment quantity of the underground water is calculated. The method achieves replenishment of hydrogeological underground water, provides a novel reliable method, promotes development of a hydrogeological discipline, scientifically and reasonably determines the planar potential replenishment quantity of regional underground water, facilitates optimal allocation of an underground water resource, provides reliable data for water resource management, provides more detailed scientific support for further establishing economic development and ecological protection measures, can be directly applied to calculation and evaluation of a regional underground water resource, improves the applicability of a determination result, and avoids a possible error in a scale conversion process of the determination result.

Vertical migration of a plume of subsurface contamination in the vadose zone to the groundwater is prevented by forming and maintaining one or more desiccation layers in the vadose zone in or above a layer of contamination. Horizontal barrier layers are produced by injecting dry air at a specific elevation in one borehole and removing the air at another borehole. These horizontal layers act as an impermeable barrier to the vertical migration of dissolved contaminants.

The invention relates to the field of simulation test equipment, and discloses a homogeneous vadose zone simulation test device and a homogeneous vadose zone simulation test method. The homogeneous vadose zone simulation test device comprises columns and rainfall simulation devices arranged at the top ends of the columns, wherein the columns are vertically arranged; each column comprises a plurality of barrels which are axially detachably connected; each column has the axial length of 4-6m, and sampling holes are formed in the side wall of each column. In such a manner, when the column is filled with soil into, the barrels can be sequentially filled with the soil from bottom to top and are assembled. The homogeneous vadose zone simulation test method comprises the step of performing a simulation test by using the homogeneous vadose zone simulation test device. In such a way, soil filling operation is easier, and the compacting effect is easier to control; in addition, the longitudinaldepth is 4-6m, close to the thickness of a natural soil cover, so that the natural geological environment of a vadose zone can be better simulated; the rainfall simulation device can simulate a natural rainfall condition and better restore the real environment in the nature, so that overall, the simulation effect is better.

The invention discloses an underground water environment simulation method and device based on aeration zone-aquifer coupling. The underground water environment simulation method based on aeration zone-aquifer coupling comprises the following steps: acquiring environment data of a research area; constructing an aeration zone-aquifer water flow and solute migration and transformation coupling model of the research area based on the environmental data; and according to the vadose zone-aquifer water flow and solute migration and transformation coupling model, determining the underground water environment distribution characteristics and evolution trend of the research area. According to the underground water environment simulation method and device based on aeration zone-aquifer coupling disclosed by the embodiment of the invention, an effective means is provided for accurately judging the pollution path, range and degree of a pollution source to underground water.

A system for intercepting, treating and venting vapors from contaminated soil in the vadose zone and from contaminated groundwater includes a large borehole and at least one small borehole each having an open top end, a porous liner against the outer wall and porous fill material inside the liner. The fill material can include materials to retard and degrade contaminants in the vapors. The large and small boreholes can have impermeable sections in the liner, and impermeable ground cover around the top ends. The large borehole can also include a slotted aeration tube in the borehole and vegetation planted in the open end of the borehole. A method for intercepting, treating and venting of vapors from contaminated soil in the vadose zone and contaminated groundwater includes the system and pulling vapors out the top end of the large borehole with variations in atmospheric barometric pressure.

The invention discloses an underground closed conduit type phreatic water replenishing system. The system comprises a head junction, a closed conduit infiltration system and an operation monitoring system, wherein the head junction and the closed conduit infiltration system are sequentially connected, and the operation monitoring system is used for monitoring the operation condition of the phreatic water replenishing system; the head junction is arranged on the ground surface and used for providing water for replenishment; the closed conduit infiltration system is embedded in a sand gravel vadose zone and used for replenishing the water for replenishment to a water-bearing layer in a leakage mode through an inside and outside water head difference so as to increase groundwater reserves; the operation monitoring system is used for monitoring hydrological and meteorological data of a replenished zone. According to the underground closed conduit type phreatic water replenishing system, the defects of a tube well injection method and a ground infiltration method which are widely applied at the present stage can be compensated, exertion of the groundwater regulation and storage function can be promoted, regional water resources can be reasonably regulated, ground surface runoff is not caused, the evaporation loss is reduced, and the water content of vegetation root layer soil can be effectively controlled; the maintenance difficulty can be reduced, blocking of the water-bearing layer of the replenished zone can be prevented, and the occupied area is reduced.

A Vadose Zone Water Fluxmeter (WFM) or Direct Measurement WFM provides direct measurement of unsaturated water flow in the vadose zone. The fluxmeter is a cylindrical device that fits in a borehole or can be installed near the surface, or in pits, or in pile structures. The fluxmeter is primarily a combination of tensiometers and a porous element or plate in a water cell that is used for water injection or extraction under field conditions. The same water pressure measured outside and inside of the soil sheltered by the lower cylinder of the fluxmeter indicates that the water flux through the lower cylinder is similar to the water flux in the surrounding soil. The fluxmeter provides direct measurement of the water flow rate in the unsaturated soils and then determines the water flux, i.e. the water flow rate per unit area.